Adipic acid is an important intermediate raw material for polyamide 66 and polyurethane. A method in which cyclohexanone and/or cyclohexanol is oxidized by nitric acid to synthesize adipic acid is industrially the mainstream as a method for producing adipic acid. A method (1) for synthesizing a ketone alcohol oil (KA oil; a mixture of cyclohexanone and cyclohexanol) by oxidization of cyclohexane, and a method (2) for synthesizing cyclohexanol by hydration of cyclohexane have been known as the method for producing cyclohexanone and/or cyclohexanol. In the production of adipic acid, a method through the method (2) for synthesizing cyclohexanol is preferable in that the method is costly advantageous as compared with a method through the method (1) for synthesizing a KA oil.
As described in Patent Document 1, a method for bringing a crystalline metallosilicate used as a solid catalyst into contact with cyclohexene in a liquid phase has been known as the method for producing cyclohexanol by hydration of cyclohexene.